Heat exchanger

ABSTRACT

A novel heat exchanger is formed by using alternating smooth and dimpled, thin, thermally conductive strips which are wound in a spiral to form the closed passageways for fluid between the strips and retain between an outer retaining and fluid distribution ring and an inner retaining and fluid distribution ring. The strips have means for sealing and insulating the periphery in a fluid tight manner. The dimpled strips have dimples extending from each side of the strip the size determining the fluid capacity of the passageways. The smooth and dimpled strips are used in pairs enabling two, four, etc., fluids to be passed either in concurrent or counter-current flow so as to provide an efficient heat exchanger which may be easily taken apart and cleaned for good service.

United States Patent Schnitzer et a1.

[451 Nov. 25, 1975 Primary Examiner-Charles J. Myhre Assistant ExaminerTheophil W. Streule Attorney, Agent, or Firm-Hubbard, Thurman, Turner & Tucker [57] ABSTRACT A novel heat exchanger is formed by using alternating smooth and dimpled, thin, thermally conductive strips which are wound in a spiral to form the closed passageways for fluid between the strips and retain between an outer retaining and fluid distribution ring and an inner retaining and fluid distribution ring. The strips have means for sealing and insulating the periphery in a fluid tight manner. The dimpled strips have dimples extending from each side of the strip the size determining the fluid capacity of the passageways. The smooth and dimpled strips are used in pairs enabling two, four, etc., fluids to be passed either in con- .current or counter-current flow so as to provide an efficient heat exchanger which may be easily taken apart and cleaned for good service.

9 Claims, 4 Drawing Figures US. Patent Nov. 25, 1975 Sheet1of2 3,921,713

US. Patent Nov. 25, 1975 Sheet2of2 3,921,713

HEAT EXCHANGER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a heat exchanger. More specifically, the present invention is directed to a heat exchanger formed by alternating smooth and dimpled, thin, thermally conductive strips wrapped in a spiral.

2. Prior Art U.S. Pat. No. 2,999,796

SUMMARY OF THE INVENTION The present invention is directed to a heat exchanger wherein alternating smooth and dimpled, thin, thermally conductive strips are wrapped in a. spiral to form the closed passageway. The dimpled strip has dimples extending from each side of the strip, the size and shape determining the fluid capacity of the passageway. The strips are utilized in pairs using either two, four or six or more alternating smooth and dimpled to form the closed passageways for the fluid. The strips are retained within an inner and outer retaining and fluid distribution ring. The strips are attached to the inner and outer retaining and fluid distribution rings at spaced points by the ends of the strips. Ports are located in the sides of the distribution rings between the spaced points for fluid to pass into or out of the passageways formed by the strips. Rubber gaskets seal the side edges of the strips and plastic or other material may be used as suitable insulating means so as to maintain the strips in a spiral between the inner and outer retaining fluid distribution ring in a fluid tight manner. In one of its more specific aspects, the present invention utilizes four strips alternating one smooth, one dimpled, another smooth, another dimpled, so as to form a tetra-fluid counterflow heat exchanger which may be easily disassembled for cleaning of any materials depositing on the strips or other operating problems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of the heat exchanger of the present invention with a partial cut away of a section;

FIG. 2 is a top view of the heat exchanger of the present invention with partial cut aways showing the strips attached to the inner and outer retaining and fluid distribution rings;

FIG. 3 is a partial cross-section of a section of the heat exchanger showing the alternating strips in the spiral, and

FIG. 4 is a partial top view of the heat exchanger of the present invention with partial cutaway showing dimples of different size on the sides of the dimpled strip with fluid passageways having different capacity.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, heat exchanger has an outer retaining and fluid distribution ring 11 and an inner retaining and fluid distribution ring 12. The outer and inner retaining and fluid distribution rings 11 and 12 are made of rigid, non-porous materials, preferably with good insulation characteristics. A suitable material is a plastic such as phenolic resins. Between the rings 11 and 12 are pairs of alternating smooth and dimpled, thin, thermally conductive strips. The one end 13 of a smooth strip 14 is held in' a slot 15 in the outer retaining and fluid distribution ring 11. The slot 15 may be formed by a drilled hole oflarger dimension than the slit fromthe inner surface of distribution ring 11 to the drilled hole. Alternatively, the slot 15 may be V-shaped with the small end at the surface of the retaining or distribution ring. The end 13 of the strip may be bent so as to form an enlarged portion with the slit or small portion of the V being essentially the size of. the strips thickness. A sealant may be forced into the slot 15 after the end 13 of the strip is in the slot 15 so as to completely seal the end 13. The end 13 of a dimpled strip 16 is held in a similar slot 15 within the inner circumference of outer retaining and fluid distribution ring 11. The dimpled strip 16 is wound with the smooth strip 14 such that when it passes the slot 15, the strips alternate as they are wound in a spiral. It is to be understood that while two strips, one smooth l4 and one dimpled 16 are described, that any number of pairs of smooth and dimpled strips may be wound in the spiral. The length of the strips are sufficient so that when wound in the spiral tightly they will fill the gap between outer retaining and fluid distribution ring 11 and inner retaining and fluid distribution ring 12.

The dimpled strip 16 has dimples which extend from each side of the strip, as more clearly seen in the crosssection in FIG. 3. In FIG. 3, reference will be made to two pair of strips, the second smooth'strip 18 alternating with a second dimpled strip 17. In the embodiment of FIG. 3 the dimples l9 and 20 on one side of the dimpled strip 16 are of the same size and shape as dimples 21 and 22 on the other side although offset from one another. Likewise, the dimples 23 and 24 on one side of dimpled strip 17 are ofthe same size and shape as dimples 25 and 26 on the other side. This embodiment therefore is one in which four passageways of the same fluid capacity are formed. It is understood however, as shown in FIG. 4, dimples 19a on one side of dimpled strip 16a may be of different size or shape from dimples 21a on the other side of dimpled strip 16a such that the fluid passageway between the strips may have different fluid capacity. Likewise while a spherical shape of dimple is shown in FIG. 2, it is understood that the shape may be of any configuration provided that the strip is not punctured or weakened mechanically by the formation of the dimple.

The other end of the strips are retained in the inner retaining and fluid distribution ring 12 in the same manner as the outer retaining and fluid distribution ring 11. An end 27 is maintained in a slot 28 in the inner retaining and fluid distribution ring 12. Each end of the strips wrapped in the spiral will be attached to the inner retaining and fluid distribution ring 12 at a different and spaced point. A fluid port 29 in the outer retaining and fluid distribution ring 11 will pass fluid through the ring 11 such that the fluid will be between the ring and dimpled strip 16. Another fluid port 30 in the outer retaining and fluid distribution ring 1 1 passes fluid so that it will be between the ring 1 l and smooth strip 15. Similarly, fluid ports 31 and 32 are shown in the inner retaining and fluid distribution ring 12. The ports are between the fixed end of the strips in the respective rings 11 and 12. The fluids as they are forced either from the inside to the outside or the outside to the inside of the heat exchanger 10 thus pass in a closed passageway formed by the alternating strips.

Referring to FIG. 3 a soft rubber gasket 33 at one side edge of the strips and another gasket 34 at the other side edge is used to close the passageways in a fluid tight manner. The soft rubber gasket 33 and 34 are preferred since the sides of the strips will embed into the rubber gaskets forming a fluid tight seal. While not shown, several rubber gaskets of varying hardness may be used but it is preferred to utilize a plastic insulating cover 35 and 36 to complete the sealing and insulation of the side edge of the strips, or to use rigid metal back plates with insulation between the plate and the rubber seal.

The heat exchanger is assembled by placing the alternating smooth and dimpled strips wrapped in the spiral between the outer retaining and fluid distribution ring 11 with the end of the strips held within the respective slots and the other ends held within slots in the inner, retaining and fluid distribution ring 12. The gaskets 33 and 34 are placed on either side of the strips as well as the insulating covers 35 and 36. Bolts 37 are used which extend through the cover 35 on one side, the outer retaining and fluid distribution ring 11 to the other insulating cover 36 and can be tightened so that there is no leakage of fluid. Similarly, bolt 38 are in a ring to tighten the inner portion through inner retaining and fluid distribution ring 12.

By the construction of the heat exchanger 10 according to the present invention it can be seen that the entire heat exchanger may be easily disassembled for cleaning. Such a heat exchanger can easily handle fluids such as salt water or chemicals of a highly corrosive or fouling nature because the heat exchanger can be easily disassembled, the strips separated and cleaned and then easily assembled for good service. Further, it has been found that heat exchangers built according to the present invention have efficiencies over 95 percent. These features are not found in heat exchangers of the prior art.

The nature and object of the present invention having been completely described and illustrated, and the best mode thereof contemplated set forth, what we wish to claim as new and useful and secure by Letters Patent is: p

l. A heat exchanger whichcomprises:

an outer retaining and fluid distribution ring,

at least one pair of alternating smooth and dimpled thin, thermally conductive strips wound in a spiral which are attached to said outer fluid distribution ring at different points, said dimpled strip having t dimples extending substantially outwardly from the plane of said dimpled strip from each side of said strip,

an inner retaining and fluid distribution ring to which said strips are attached at spaced points, and

means for sealing and insulating the side edge of said strips in a fluid tight manner thereby forming at least two closed passageways between said thermally conductive strips in spiral pathways between said outer retaining and fluid distribution ring and said inner retaining and fluid distribution ring.

2. A heat exchanger according to claim 1 wherein.

there are two fluid ports in said outer retaining and fluid distribution ring and said inner retaining and fluid distribution ring for each pair of spiral strips, said ports communicating with said closed passageways.

3. A heat exchanger according to claim 1 wherein four strips are alternatively spiraled.

4. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on both sides of substantially the same size andshape forming closed passageways of the same fluid capacity.

5. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on one side of substantially different size and shape than the dimples on the other side forming closed passageway of different fluid capacity.

6. A heat exchanger according toclaim 1 wherein the ends of said strips have enlarged portions greater than: the thickness of the strip and are held in slots in said inner and outer retaining and fluid distribution rings by said enlarged portions.

7. A heat exchanger according to claim 6 wherein the ends of said strips are sealed by filling said slots with a sealant.

8. A. heat exchanger according to claim 6 wherein said slots are formed by drilled holes and slits in said inner and outer retaining and fluid distribution rings.

9. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on one side of substantially different size than the dimples on the other side forming closed passageways of different fluid capacity. 

1. A heat exchanger which comprises: an outer retaining and fluid distribution ring, at least one pair of alternating smooth and dimpled thin, thermally conductive strips wound in a spiral which are attached to said outer fluid distribution ring at different points, said dimpled strip having dimples extending substantially outwardly from the plane of said dimpled strip from each side of said strip, an inner retaining and fluid distribution ring to which said strips are attached at spaced points, and means for sealing and insulating the side edge of said strips in a fluid tight manner thereby forming at least two closed passageways between said thermally conductive strips in spiral pathways between said outer retaining and fluid distribution ring and said inner retaining and fluid distribution ring.
 2. A heat exchanger according to claim 1 wherein there are two fluid ports in said outer retaining and fluid distribution ring and said inner retaining and fluid distribution ring for each pair of spiral strips, said ports communicating with said closed passageways.
 3. A heat exchanger according to claim 1 wherein four strips are alternatively spiraled.
 4. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on both sides of substantially the same size and shape forming closed passageways of the same fluid capacity.
 5. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on one side of substantially different size and shape than the dimples on the other side forming closed passageway of different fluid capacity.
 6. A heat exchanger according to claim 1 wherein the ends of said strips have enlarged portions greatEr than the thickness of the strip and are held in slots in said inner and outer retaining and fluid distribution rings by said enlarged portions.
 7. A heat exchanger according to claim 6 wherein the ends of said strips are sealed by filling said slots with a sealant.
 8. A heat exchanger according to claim 6 wherein said slots are formed by drilled holes and slits in said inner and outer retaining and fluid distribution rings.
 9. A heat exchanger according to claim 1 wherein the dimpled strip has dimples on one side of substantially different size than the dimples on the other side forming closed passageways of different fluid capacity. 